I was reading an article recently in Outsource Magazine which was a pretty comprehensive view of the Sales Outsourcing space. Some key quotes from the article "Selling the Family Silver?" (issue 3) are:

"In direct sales, there are 3 main elements to engaging with a customer...and it is always the least relationship-driven aspects of these [lead generation, making appointments, telesales and telemarketing] that are the most likely candidates for outsourcing."

"New business creation is the least complex to outsource, and this is reflected in market demand."

"A number of UK companies have more than 40 to 45 per cent of their sales force outsourced because it brings in best practice and internal competition to the industry and it also frees up internal resources and people"

"Organisations that often choose to go down the outsourcing route are startups and small businesses because the move enables them to reduce their overheads, improve their cash-flow and access different skill sets as and when they need them."